JP2006521157A - Moire aberration measuring instrument - Google Patents

Abstract

An improved moire deflectometer device (100) for measuring the wavefront aberration of an optical system (110) comprises a light source (120) for illuminating a surface region (112) of the optical system, a moire fringe pattern on the wavefront An optical relay system (140) for directing scattered light to a deflection meter component (150) that converts to an optical sensor, an exit pupil (114) of the optical system and a sensor / camera for imaging and displaying the moire fringe pattern A fringe pattern for calculating the wavefront aberration of the optical system, improved by an illumination source (130) for illuminating the assembly (160) and the exit pupil (114) of the optical system; and Align the measurement axis of the device with the optical system and accurately align it In so that manner, it comprises an alignment system (180) which cooperates with the illumination source.

Description

(Background of the Invention)
(Field of Invention)
The present invention relates primarily to an eye wavefront sensing apparatus and method, and more specifically to a wavefront sensor apparatus and method based on the moire deflection meter principle.

(Description of related technology)
Measurement of eye wavefront aberrations up to the 10th-order Zernike term continues to find increasing applications in the field of ophthalmology, particularly with respect to refractive procedures such as LASIK, LASEK, PRK and other surgical procedures. ing. For vision correction, it is no longer sufficient to simply measure the local anatomy of the cornea to determine how best to reshape the human cornea. And while the corneal topography system used in combination with pachymetry devices and ray tracing technology can provide a lot of information about human eye and vision problems, aberration measurement is by itself Provides unique information about the visual impairment of the entire optical system. Wavefront sensing is used to create and order custom ophthalmic lenses (eg contact lenses, IOLs, etc.) from traditional refraction measurements for the correction of defocus and astigmatism. It has a range of applications up to its contribution to the corresponding laser ablation procedure, which has the ability to provide vision improvement to the theoretical limit of the human eye.

  The aberrometer and the principle on which it works can generally be classified into four types: (1) out-going (eg, Hartmnam-Shack); (2) double-pass (eg, Slit skioscopy); (3) in-going accommodation (eg, spatially resolved refractometer); and (4) retinal image aberration measurement methods (eg, Tschering, Tracey). In the environment currently on the market, aberration measurement methods based on Hartmann-Shack wavefront sensors are most commonly performed. However, Hartmann-Shack and other wavefront measurement principles embodied in various commercially available devices each have relatively identifiable advantages and disadvantages. Interesting readers will provide a detailed review of urf, which provides a detailed review of ophthalmic aberration measurements based on the minutes of First International Congress of Wavefront Sensing and Aberration-Free Refractive Correction, ur f No. 5 (September / October 2000).

  Ophthalmic wavefront sensing and analysis is in no way limited to the above classifications. Researchers in the field of psychophysics (for example, Smirnov in the 1960s, Howland in the mid-1980s, and Liang and Williams in the late 80s and mid-90s) acquired ocular aberration data and Various optical principles were used for analysis. Similarly, a great deal of know-how for ophthalmic applications has been transferred from the fields of astronomy, strategic defense initiatives, and optical lens testing.

  In International Patent Application Publication No. WO 92/01417, Horwitz discussed automated binocular vision measurement and correction by moire fringe generation and analysis (commonly known as a moire deflection meter). This publication claims to have the ability to measure up to 256 aberrations of the eye, and the design and manufacture of binocular devices and ophthalmic lenses made to order, as well as of this technology for laser refractive surgery. Application was described. In 1999, Horwitz U.S. Pat. No. 5,963,300 discloses an ophthalmic biometer based in part on the moire deflection measurement method and provides a limited teaching of Fourier analysis to provide wavefront aberration information. Included. Despite the issuance of the '300 patent, the application of technology to eye wavefront sensing still seemed to require something else. Something is described in Quiroga et al., Fourier transform method for automatic processing of moire defractograms, Opt. Eng. 38 (6) 974-982 (June 1999).

  The measurement limits of Hartmann-Shack type aberrometers and their size, cost and complexity are issues that are well recognized by those skilled in the art. The inventor has recognized that improvements to the moire deflectometer apparatus and method can advantageously address many of the issues associated with current aberrometer technology. Accordingly, the present specification provides a Hartmann-Shack type and other commercially available ophthalmic aberrometer systems that the inventor believes to provide wavefront measurements with better resolution, higher reliability, and accurate analytical performance. An improved moire deflection meter apparatus and method that is simpler, less expensive and more robust is disclosed.

(Summary of the Invention)
Embodiments of the present invention relate to a device for measuring wavefront aberrations of an optical system (preferably in a living human eye and a test object intended for calibration purposes). The device embodied by the present invention is based on the moire deflection meter principle. The Moire flexometer is a light source used to prove the selected surface area of the optical system under test, a proof of the light source scattered from the surface area of the optical system, and a moiré fringe of the exit wavefront from the optical system. An optical relay system for directing to a deflection meter that converts to a pattern, a sensor / camera assembly that detects the moire fringe pattern, and a fringe pattern analyzer used to calculate the wavefront aberration of the optical system; The improvement here is that the illumination source used to prove the exit pupil of the optical system, and the optical system under test are aligned and precisely aligned with the defined measurement axis of the device. Characterized by an alignment system that provides capabilities. Preferred aspects of embodiments of the present invention include: The light source is a parallel having a cross-sectional diameter greater than the diffraction limited size up to about 1 mm at the front surface (eg, tear film / cornea) of the optical system. It emits coherent light in the form of a beam. The propagation axis of the parallel beam at its front surface is offset parallel to the optical axis of the optical system by about 1 mm. A preferred wavelength is about 780 nm. The deflection meter comprises a first square grid having periodic grid lines orthogonal to each other and a second (preferably identical) square grid. The two square grids are located on the optical axis, and the grid lines of the first grid correspond to the detector alignment in the sensor / camera assembly, corresponding to x in the xy plane of the Cartesian coordinate system. Aligned along the axis and the y-axis. The second square grid is located at a Talbot distance of 1 or more times downstream of the first square grid and is at an angle θ between 0 ° and 90 ° with respect to the first grid (but at both ends) In the xy plane. The sensor / camera assembly is preferably a CCD detector camera associated with a lens for focusing the moiré fringe pattern on the detector. The illumination source is preferably controllable to a far IR source and provides uniform illumination of the exit pupil of the optical system during the alignment phase of the wavefront measurement, and during the acquisition phase of the wavefront measurement. The exit pupil of the optical system cannot be illuminated. The device further preferably includes an alignment system having software generated crosshair markings on the camera display to provide identification of the center position of the exit pupil along the measurement axis of the device.

  The present invention will become more readily apparent from the following detailed description. However, it should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are given by way of illustration only. This is because various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art based on the detailed description and drawings, and appended claims.

Detailed Description of the Preferred Embodiments of the Invention
An embodiment of a moire wavefront sensor device 100 according to the present invention is illustrated in FIG. This device (essentially a Moire flexometer) measures and analyzes the wavefront aberration of the optical system 110. The optical system of interest includes living human eyes and test objects for calibration purposes, but the present invention is not limited to measuring these objects. The system 110 functions as a single optical path wavefront measurement system, which term is understood in the art. That is, a point source of light of the appropriate spot diameter is created on the back diffusing surface 112 of the optical system; ie, the retina. The rear surface 112 reflects and scatters in the form of a wavefront 125 to diffuse small points of light away from it through the optical system 110.

The basic principle of operation of the device disclosed herein is based on Talbot imaging. Talbot imaging is a diffraction phenomenon that occurs on a periodic object (eg, a transmissive diffraction grating). Under appropriate illumination with plane waves, a complete replica of the object appears at a fixed distance, referred to as the Talbot plane, as illustrated in FIG. The position of the Talbot plane Z _j depends on the period p of the object and the wavelength λ of light according to the relationship Z _j = p ² j / λ. If the illuminated wavefront is deflected, the Talbot image is distorted as illustrated in FIG. The amount of distortion is based on the wavefront slope in a direction perpendicular to the grid orientation of the object. Crossed gratings (illustrated in FIG. 4 and detailed below) can be used to recover their wavefront slopes in two orthogonal directions. For large grating periods, the distorted Talbot image can be acquired and analyzed for convenience. However, to increase the resolution, a finer grating period positions the second grating in one of the subsequent Talbot planes and rotates the second grating in the plane of the first grating object. Can be used. This produces a moire effect as illustrated in FIG. The superposition of the distorted Talbot image and the second grid produces a moire fringe pattern. The shape of the moire pattern is related to the inclination of the wavefront, as illustrated in FIG.

  The apparatus 100 includes a light source 120 suitable for illuminating a selected surface area 112 of the optical system 110, an optical relay system 140 (for directing light scattered from the surface area of the optical system to a flexure 150. This produces a moire fringe pattern 500 from the exit wavefront 125). A sensor / camera assembly 160 is provided and analyzed by a moire fringe pattern, which is analyzed by a fringe pattern analyzer 170 (eg, a programmed personal computer) to provide various advantages associated with vision measurement and vision correction methods and apparatus. Can be provided in such a manner as to obtain wavefront aberration information for a specific purpose. The device 100 includes an illumination source 130 for providing illumination imaging of the exit pupil 114 of the optical system, and an alignment system that facilitates consistent alignment and measurements associated with a coordinate system 190 associated with the device shown. 180 is further provided. The device has an orientation relative to the Cartesian coordinate system shown in FIG. 1; that is, the z-axis 185 represents the representations the measurement axis of the device, and the various lenses, gratings and detectors / cameras can be And in the xy plane aligned with respect to the y-axis.

  In a preferred embodiment according to the present invention, the optical system 110 is a living human eye and the surface area 112 of the posterior surface is the foveal area of the retinal surface of the eye. The light source 120 illuminates to illuminate selected surface areas of the optical system substantially in the form of a point source of light. The light source 120 may be any suitable light source known to those skilled in the art that emits coherent light, preferably having a wavelength in the near IR spectrum. The wavelength range is preferably between about 770 nm and 790 nm, most preferably about 780 nm. Well known means such that the illumination 121 is in the form of a collimated beam of light having a cross-sectional beam diameter in a range slightly larger than the diffraction limit up to about 1 mm at or near the front surface 116 of the optical system. Is adjusted from either inside or outside the light source 120. In preferred ophthalmic embodiments, the collimated light incident on the eye is between about 300 microns and about 1000 microns, more preferably between about 600 microns and 1000 microns at the cornea / tear membrane surface of the eye. Beam diameter. The collimated beam 121 preferably has a propagation axis 118 that is offset parallel to the system z-axis 185 by a distance of about 1 mm. The deviation of the incident beam is a specular reflection; for example, a reflection from the other surface of the optical system that can obscure a first Purkinje image from the corneal surface and a weak retinal reflection containing the wavefront information to be measured, Eliminate. It will be appreciated by those skilled in the art that small deviations in the corneal surface and small beam diameter reduce the corneal inductive aberrations of the incident beam.

  It is well known that in a normal eye, the plane wavefront incident on the eye is collected at points on the retina surface. However, myopic or hyperopic eyes, respectively, focus the same incident wavefront at a point in front or behind the retina, so that the light spot on the retina surface is no longer a convenient measure of wavefront error or even It is not a point radiation source of a size suitable for possible measurements. As disclosed herein, a small diameter incident beam (referred to as direct incidence due to eliminating the need for any refractive components in the optical path between the light source and the object) It has been demonstrated to avoid the problem of defocusing myopia and hyperopia without using external focusing optics, polarization optics, or optical path length adjustment. The preferred refractive optical measurement range is between -12 and +6 diopters, more preferably between ± 20D. Direct incidence of illumination light is described in co-pending patent application no. 10/0273777 (titled ABERROMETER ILLUMINATION APPARATUS AND METHOD, filed on Dec. 21, 2001 and shared with the applicant). One reader is also directed to Williams et al., US Patent No. 6,264,328 for a detailed discussion of wavefront sensors with off-axis illumination, both of which are applicable patent laws and regulations. Fully incorporated herein by reference to the extent permitted by.

  The retinal surface of the eye or the posterior surface of the optical system reflects diffusely and scatters the point source of light to form a flexible wavefront 125 that moves away from the optical system. A relay system 140, well known to those skilled in the art, directs propagation of the wavefront 125 to a deflection meter 150 described below.

  The deflection meter 150 includes two components 151 and 151 '. The components each have a grid of equally periodically orthogonal grid lines 152, 152 ′; for example, each component is a mesh of crossed square grids as shown in FIG. In the present specification, they are referred to as a first square grid 151 and a second square grid 151 ′). The grid lines 152 (152 ') are preferably laser etched into the glass substrate, but are not so limited in the construction according to the present invention. The square grids 151, 151 'are preferably identical. The same square grid 151 is positioned along its measurement axis 185 to cut out a wavefront 125 that moves from left to right as shown in FIG. As illustrated in more detail in FIG. 4, the first square grid 151 is aligned in the xy plane so that the horizontal grid lines are parallel to the x axis and the vertical grid lines are Parallel to the y-axis of the device coordinate system. Most preferably, the detector portion of the sensor / camera assembly 160 is also in substantially the same alignment with the first square grid 151 in the xy plane. Failure to combine these alignments makes it difficult to decouple aberrations measured along the x and y axes, if not impossible. This is preferred for ophthalmic wavefront sensing applications. The just described coalignment may be a structurally fixed characteristic of the device. The second square grid 151 ′ is offset downstream of the first square grid along the z-axis by a distance nT as shown in FIG. 1, where T is the Talbot distance and n is an integer It is. In a preferred embodiment, n = 1. In the device, the second square grid 151 ′ is selectively and fixedly tilted in the xy plane by an angle θ (where 0 ° <θ <90 °) with respect to the first component. . Quiroga et al., Fourier transform method for autoprocessing processing, opt. Eng. 38 (6) 974-982 (June 1999), which is hereby incorporated by reference in its entirety to the fullest extent permitted, where the typical arrangement of the lattices, where the lattices are θ / 2 And the rotation of the grating symmetrically with respect to the reference axis by −θ / 2) has been shown to be not well suited to completely separate the x and y components of the wavefront gradient. The results obtained for the deflection are as follows:

である。これらの等式は、グリッドについての標準的な対称的配置を用いると、ｘ方向およびｙ方向におけるたわみの完全な分離を得ることができないことを示す。θ＝０の場合、そのたわみは、分離されるが、その縞出力のフーリエ分析に必要とされる空間的キャリアは存在しない。最も大きな空間的キャリアが、好ましい。従って、θは、ｓｉｎθ／２≠０である程度に十分な値でなければならず、θ_ｍａｘは、ＣＣＤアレイのサイズおよびグリッド間隔Ｐのサイズに依存する。なぜなら、その増幅定数（ａｍｐｌｉｆｉｃａｔｉｏｎ ｆａｃｔｏｒ）Ｐ’＝Ｐ／θであるからである。θが大きすぎると、ＣＣＤアレイ上で縞を画像化することが困難になり得る。θが小さすぎると、その空間的キャリアが危険になる。モアレたわみ計および分析のより詳細な議論に興味のある読み手は、ＫａｆｒｉおよびＧｌａｔｔ 標題Ｔｈｅ Ｐｈｙｓｉｃｓ ｏｆ Ｍｏｉｒｅ Ｍｅｔｒｏｌｏｇｙ，Ｊｏｈｎ Ｗｉｌｅｙ ＆ Ｓｏｎｓ，Ｎｅｗ Ｙｏｒｋ（１９９０）（最大限認められる範囲まで本明細書にその全体が参考として援用される）によりそのテキストに指示される。

It is. These equations show that with standard symmetric arrangements for the grid, complete separation of deflections in the x and y directions cannot be obtained. When θ = 0, the deflection is separated, but there is no spatial carrier required for Fourier analysis of the fringe output. The largest spatial carrier is preferred. Therefore, θ must be a value sufficiently large so that sin θ / 2 ≠ 0, and θ _max depends on the size of the CCD array and the grid interval P. This is because the amplification factor P ′ = P / θ. If θ is too large, it may be difficult to image the stripes on the CCD array. If θ is too small, the spatial carrier becomes dangerous. Readers interested in a more detailed discussion of Moire flexometers and analysis should read Kafri and Glatt title The Physics of Moire Metrology, John Wiley & Sons, New York (1990) (to the fullest extent permitted herein) Is incorporated into the text by reference).

  A fringe pattern sensor / camera assembly 160 (preferably comprising a CCD detector and camera) is provided in part to detect moire fringes and send this data to the fringe analyzer 170. The sensor / camera assembly 160 is also used to image and display the exit pupil of the optical system; ie, the pupil of the eye. In this regard, the device 100 further comprises an illumination source 130 and an alignment system 180 that is cooperatively engaged. The light emitted by the illumination source 130 should illuminate the exit pupil plane uniformly. The light does not change the pupil size due to the light response, but at the same time is in the far IR spectrum in the wavelength range that can be detected by the camera to image the exit pupil. Although a wavelength of about 880 nm has been shown to be effective, other wavelengths can also be used, as one skilled in the art will recognize. In operation, the illumination source is in illumination mode (on) during patient eye alignment. While the wavefront measurement is taking place (referred to as measurement mode), the illumination source is in a non-illumination mode (off or otherwise prevented from illuminating the eye). In an exemplary embodiment, the illumination source is in the form of a full or partial ring of LEDs suitably arranged to illuminate the exit pupil plane uniformly.

  In order to accurately and consistently measure wavefront aberration, the measurement axis 185 of the device 100 and the eye to be measured must be accurately and consistently aligned. If the exit pupil of the optical system is not properly centered and aligned, the exit pupil image may appear as a normally circular image, but this image may be unnoticeably blurred due to misalignment. Failure to center and align the device consistently can result in different wrong wavefront measurements from the eye being measured each time a measurement is taken. As part of the alignment system 180 and associated procedures, a crosshair mark 315 as illustrated in FIG. 8 is provided to assist in centering the exit pupil 114 with respect to the measurement axis 185 of the device. This pupil can be observed directly through the camera 160. In a preferred embodiment, the crosshair mark is implemented in software and displayed with an image of the eye pupil to allow the user to focus repeatedly on the center of the pupil. Other alignment schemes are possible. For example, the visual axis can be used for alignment instead of the center of the pupil. The important point is to align the exit pupils consistently as each measurement is made.

  The optical components of the device (reticle, lens, detector, etc.) should be sufficient to preferably measure exit pupils having a diameter of up to 8 mm. This magnitude represents the substantial pupil diameter for measurement and correction of higher order aberrations than custom lenses or refractive surgery (eg, custom LASIK, LASEK, PRK, etc.). Larger measurement capabilities may be desirable. A dynamic measurement range of ± 20 diopters is preferred.

  The fringe pattern analyzer 170 is cooperatively engaged with the sensor 160 and is programmed to calculate wavefront aberrations based on an analysis of the detected moire fringes. The analysis procedure for Moire fringe pattern contours (Talbot interferograms, shadow patterns) for wavefront aberration calculations is described in Herwitz US Pat. No. 5,963,300 (to the fullest extent possible). (Incorporated herein by reference). In essence, this analysis detects the pattern of fringes (moire, Talbot, Fresnel, shadows, etc.) and digitizes it; transforms the digital image from spatial enemy regions into the spatial frequency domain. Determining the dominant harmonic; correlating the dominant harmonic with a wavefront in a defined axis; calculating a three-dimensional optical domain wavefront; and analyzing the resulting measurements did. Moire deflection diagrams are provided by Quiroga et al. One skilled in the art can use the teachings of Quiroga et al. To develop suitable software for extracting wavefront information from phase information in a flexure.

  Wavefront aberration analysis may be expressed in the form of a Zernike polynomial, which is known to those skilled in the art, such as a contact lens according to order, a lathe for design and manufacture of an IOL according to order or other It can be used to program the device as well as to develop ablation patterns used in laser refractive surgery.

  Since the device described herein can measure isolated wavefront aberrations from unfocused (secondary) to beyond the fifth order, this device is another advantageous application as an object phoropter. Have Binocular devices can also be implemented based on the principles disclosed herein. The binocular pupil measurement method is a preferred method for measuring pupil diameter because the behavior of both pupils is combined.

  While various advantageous embodiments have been selected to illustrate the present invention, changes and modifications may be made in the present invention without departing from the scope of the invention as defined in the appended claims. It will be understood by those skilled in the art that this can be done.

FIG. 1 is a schematic view of a moire deflection meter according to an embodiment of the present invention. FIG. 2 illustrates the principle of unfolded Talbot imaging of periodic objects. FIG. 3 illustrates Talbot imaging with periodic object deflection. FIG. 4 illustrates Talbot imaging with deflection of intersecting square periodic objects. FIG. 5 illustrates the moire effect resulting from the relative rotation between the first periodic object and the second periodic object. FIG. 6 illustrates the moire effect resulting from the superposition of the distorted Talbot image and the second periodic object. FIG. 7 is a schematic diagram of relative rotation between two intersecting grids in the xy plane according to an embodiment of the present invention. FIG. 8 is a schematic diagram of a camera image of the exit pupil of the optical system under test, aligned with a crosshair according to an embodiment of the present invention.

Claims (32)

A device for measuring the wavefront aberration of an optical system comprising: a light source suitable for illuminating a selected surface area of the optical system; and the light source scattered from the surface area of the optical system An optical relay system for directing the illumination of the optical system to a deflection meter component, wherein the deflection meter component adapts the wavefront from the optical system to a moire fringe pattern; and A sensor / camera assembly adapted to image and display an exit pupil of the optical system and the moire fringe pattern, and a fringe pattern analyzer adapted to calculate the wavefront aberration of the optical system ,
An illumination source for illuminating the exit pupil of the optical system; and an alignment system that cooperates with the illumination source in a manner to align the measurement axis of the device in alignment with the optical system;
Characterized by the device. The device of claim 1, wherein the light from the light source is coherent light. The device of claim 1, wherein the light from the light source is in the form of a collimated beam having a cross-sectional diameter greater than a diffraction limit of up to about 1 mm before illuminating the selected surface area of the optical system. . The device of claim 3, wherein the cross-sectional diameter is between about 300 μ and 600 μ. The device of claim 1, wherein the illumination of the light source has an incident propagation axis that is offset from a central optical axis of the optical system. The device of claim 5, wherein the deviation is about 1 mm. The device of claim 1, wherein the illumination of the light source has a wavelength in the near IR spectrum. The device of claim 7, wherein the wavelength ranges between about 770 nm and 790 nm. The device of claim 8, wherein the wavelength is about 780 nm. The deflection meter is a first square grid having equally periodic grid lines in an orthogonal direction, the grid representing the orthogonal grid lines and the horizontal and vertical axes of the sensor with respect to the reference coordinate system of the device. A first square grid in fixed alignment with the sensor to align with the x-axis and y-axis of the sensor, and further comprising a second square substantially identical to the first square grid; Here, the first grid and the second grid are located along the z-axis of the reference coordinate system at an interval nT, where n is an integer greater than or equal to 1 and T is a Talbot distance. And wherein the second grid is rotated in the xy plane at an angle θ relative to the first grid, wherein θ is 0 ° <θ <90 °. Devices. The device according to claim 10, wherein θ is 1 ° ≦ θ ≦ 10 °. 11. The device of claim 10, wherein the deflection meter is a glass material having laser etched grid lines. The device of claim 1, wherein the sensor comprises a CCD camera. The device of claim 1, wherein the illumination source for illuminating the exit pupil of the optical system has a wavelength in the far IR spectrum. The device of claim 14, wherein the wavelength ranges between about 800 nm and 900 nm. The device of claim 15, wherein the wavelength is about 880 nm. The device of claim 1, wherein the illumination source has an illumination mode and a non-illumination mode. The device of claim 1, wherein the illumination source is in the form of a ring of light emitting devices that are suitably arranged to illuminate the exit pupil uniformly. The device of claim 1, wherein the alignment system comprises a crosshair marking to confirm that the center position of the exit pupil is on the crosshair. The device according to claim 19, wherein the cross mark is a mark executed by software. The device of claim 1, wherein the fringe pattern analyzer is a component adapted to perform software-driven Fourier transform analysis of the moire fringe pattern. The device of claim 1, wherein the optical system is a test lens, and the selected surface area is a diffusely reflecting back area of the test lens. The device of claim 1, wherein the optical system is an eye, and the selected surface region is a foveal region of the retinal surface of the eye. 11. The device of claim 10, wherein the first and second transmissive materials, incorporating square grid lines that are equally periodic in the orthogonal direction, are the same Ronchi stripe crossing pair. A method for measuring the wavefront aberration of an optical system using a moire deflectometer device, the method comprising the following steps:
Providing a device comprising a light source, a sensor / camera assembly, a fringe pattern analyzer, an illumination source, an alignment system, and a deflection meter component comprising first and second square grids, wherein the first The square grid has grid lines that are equally periodic in the orthogonal direction, the first square grid includes the orthogonal grid lines and the parallel and vertical axes of the sensor, the x-axis of the reference frame of the device, and In a fixed alignment with the sensor so as to align with the y-axis, where the second square grid is located downstream by a distance nT of the first square grid, where n Is an integer greater than or equal to 1, T is the Talbot distance, and the second grid is at an angle θ relative to the first grid x It is rotated and fixed in the y plane, where theta is 0 ° <θ <90 °, step;
Uniformly illuminating the exit pupil of the optical system with light from the illumination source;
Obtaining an image of the exit pupil including alignment marks;
Each time a wavefront measurement is made, the exit pupil is aligned and aligned with the alignment mark;
Illuminating selected diffusely reflecting surface areas of the optical system with a suitably sized spot of light provided by the light source; and obtaining wavefront aberration data;
Including the method. 26. The method of claim 25, wherein uniformly illuminating the exit pupil comprises using a ring of light emitting sources or at least a portion thereof. 26. The method of claim 25, wherein illuminating the exit pupil uniformly comprises using light having a wavelength in the range of 800-900 nm. 26. The method of claim 25, wherein illuminating the exit pupil uniformly includes using light having a wavelength of about 880 nm. 26. The method of claim 25, wherein aligning and aligning the exit pupil includes aligning a center of the exit pupil with a measurement axis of the device. 26. The method of claim 25, wherein aligning and aligning the exit pupil includes aligning a visual axis through the exit pupil with respect to a measurement axis of the device. 26. The method of claim 25, wherein illuminating the selected diffusely reflecting surface area comprises directly emitting a coherent beam parallel to the optical system. 26. The method of claim 25, wherein the beam has a diameter between about 600 and 1000 [mu] m.

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